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<html>
  <head>
    <meta charset='utf-8'>
    <meta name='viewport' content='width=device-width, initial-scale=1, user-scalable=no'>
    <meta name='mobile-web-app-capable' content='yes'>
    <meta name='apple-mobile-web-app-capable' content='yes'>

    <!-- Origin Trial Token, feature = WebXR Device API, origin = https://immersive-web.github.io, expires = 2018-08-28 -->
<meta http-equiv="origin-trial" data-feature="WebXR Device API" data-expires="2018-08-28" content="AnNpu7ceXvLew05ccD8Zr1OZsdZiB2hLQKK82kTTMDwF7oRKtP3QEJ4RzkeHrmB8Sq0vSV6ZNmszpBCZ0I8p9gAAAABceyJvcmlnaW4iOiJodHRwczovL2ltbWVyc2l2ZS13ZWIuZ2l0aHViLmlvOjQ0MyIsImZlYXR1cmUiOiJXZWJYUkRldmljZSIsImV4cGlyeSI6MTUzNTQxNDQwMH0=">

    <title>AR Hit Test</title>

    <link href='../css/common.css' rel='stylesheet'></link>

    <!--The polyfill is not needed for browser that have native API support,
        but is linked by these samples for wider compatibility.-->
    <!--script src='https://cdn.jsdelivr.net/npm/webxr-polyfill@latest/build/webxr-polyfill.js'></script-->
    <script src='../js/xrray-polyfill.js' type='module'></script>
    <script src='../js/webxr-polyfill.js'></script>

    <script src='../js/webxr-button.js'></script>
  </head>
  <body>
    <header>
      <details open>
        <summary>AR Hit Test</summary>
        <p>
          This sample demonstrates use of hit testing to place AR objects on real-world surfaces.
          <a class="back" href="./index.html">Back</a>
          <br/>
          <hr/>
          <input id="useReticle" type="checkbox" checked>
          <label for="useReticle">Use reticle for placement</label><br/>

          <input id="useDomOverlay" type="checkbox" checked>
          <label for="useDomOverlay">Enable DOM Overlay</label><br/>
        </p>
      </details>
    </header>
    <script type="module">
      import {Scene} from '../js/cottontail/src/scenes/scene.js';
      import {Renderer, createWebGLContext} from '../js/cottontail/src/core/renderer.js';
      import {Gltf2Node} from '../js/cottontail/src/nodes/gltf2.js';
      import {QueryArgs} from '../js/cottontail/src/util/query-args.js';
      import {FallbackHelper} from '../js/cottontail/src/util/fallback-helper.js';
      import {Node} from '../js/cottontail/src/core/node.js';
      import {RayNode} from '../js/cottontail/src/nodes/ray-node.js';
      import {DropShadowNode} from '../js/cottontail/src/nodes/drop-shadow.js';
      import {vec3} from '../js/cottontail/src/math/gl-matrix.js';
      import {DebugSources} from '../js/debug-sources.js';

      // If requested, initialize the WebXR polyfill
      if (QueryArgs.getBool('allowPolyfill', false)) {
        var polyfill = new WebXRPolyfill();
      }

      let debugSources;
      if (QueryArgs.getBool('debugSources', false)) {
        debugSources = new DebugSources();
      }

      // If requested, add a cross-origin iframe element via SVG
      if (QueryArgs.getBool('iframe', false)) {
        let iframe = document.createElement('iframe');
        iframe.src = 'data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><rect height="150" width="150" fill="red" fill-opacity="0.3"/></svg>';
        iframe.style = 'position: absolute; right: 0; bottom: 0; width: 150px; height: 150px;';
        document.body.insertBefore(iframe, document.body.firstChild);
      }

      let useReticle = document.getElementById('useReticle');
      const useDomOverlay = document.getElementById('useDomOverlay');

      // Debugging constants.
      const unsubscribeAfterTouch = false; // unsubscribe from hit test after first touch if in reticle mode?
      const visualizeOffsetSpace = false;
      const visualizeObjectSpace = false;
      const visualizeOrigin = false;
      const visualizeLocalFloorSpace = false;

      // Suppress XR events for interactions with the DOM overlay
      document.querySelector('header').addEventListener('beforexrselect', (ev) => {
        console.log(ev.type);
        ev.preventDefault();
      });

      // XR globals.
      let xrSession = null;
      let xrButton = null;
      let xrRefSpace = null;
      let xrLocalFloor = null;
      let xrViewerSpace = null;
      let xrOffsetSpace = null;
      let xrViewerSpaceHitTestSource = null;
      let xrTransientInputHitTestSource = null;

      // WebGL scene globals.
      let gl = null;
      let renderer = null;
      let scene = new Scene();
      scene.enableStats(false);

      useReticle.addEventListener('change', (ev) => {
        if (!xrSession) return;
        if (useReticle.checked) {
          requestViewerSpaceHitTestSource();
        } else {
          xrViewerSpaceHitTestSource = null;
          arObject.visible = false;
        }
      });

      // Visualise the origin.
      if (visualizeOrigin) {
        let xRay = new RayNode({direction : [5, 0, 0], baseColor : [1, 0, 0, 1]});
        let yRay = new RayNode({direction : [0, 5, 0], baseColor : [0, 1, 0, 1]});
        let zRay = new RayNode({direction : [0, 0, 5], baseColor : [0, 0, 1, 1]});

        scene.addNode(xRay);
        scene.addNode(yRay);
        scene.addNode(zRay);
      }

      // Visualise the offset space.
      let offsetSpaceNode = new Node();
      offsetSpaceNode.visible = false;

      if (visualizeOffsetSpace) {
        let xRay = new RayNode({direction : [5, 0, 0], baseColor : [1, 0, 0, 1]});
        let yRay = new RayNode({direction : [0, 5, 0], baseColor : [0, 1, 0, 1]});
        let zRay = new RayNode({direction : [0, 0, 5], baseColor : [0, 0, 1, 1]});

        offsetSpaceNode.addNode(xRay);
        offsetSpaceNode.addNode(yRay);
        offsetSpaceNode.addNode(zRay);
      }

      scene.addNode(offsetSpaceNode);

      // Visualize local floor space
      let localFloorSpaceNode = new Node();
      localFloorSpaceNode.visible = false;

      if (visualizeLocalFloorSpace) {
        let xRay = new RayNode({direction : [5, 0, 0], baseColor : [1, 0, 0, 1]});
        let yRay = new RayNode({direction : [0, 5, 0], baseColor : [0, 1, 0, 1]});
        let zRay = new RayNode({direction : [0, 0, 5], baseColor : [0, 0, 1, 1]});

        localFloorSpaceNode.addNode(xRay);
        localFloorSpaceNode.addNode(yRay);
        localFloorSpaceNode.addNode(zRay);
      }

      scene.addNode(localFloorSpaceNode);

      // -----------------------------------------------------------------------

      let arObject = new Node();
      arObject.visible = false;
      scene.addNode(arObject);

      let flower = new Gltf2Node({url: '../../media/gltf/sunflower/sunflower.gltf'});
      arObject.addNode(flower);

      // Having a really simple drop shadow underneath an object helps ground
      // it in the world without adding much complexity.
      let shadow = new DropShadowNode();
      vec3.set(shadow.scale, 0.15, 0.15, 0.15);
      arObject.addNode(shadow);

      const MAX_FLOWERS = 30;
      let flowers = [];

      // Ensure the background is transparent for AR.
      scene.clear = false;

      function initXR() {
        xrButton = new XRDeviceButton({
          onRequestSession: onRequestSession,
          onEndSession: onEndSession,
          textEnterXRTitle: "START AR",
          textXRNotFoundTitle: "AR NOT FOUND",
          textExitXRTitle: "EXIT  AR",
          supportedSessionTypes: ['immersive-ar']
        });
        document.querySelector('header').appendChild(xrButton.domElement);
      }

      function onRequestSession() {
        let options = {
          requiredFeatures: ['local-floor', 'hit-test'],
          optionalFeatures: ['anchors'],
        };
        if (useDomOverlay.checked) {
          options.optionalFeatures.push('dom-overlay');
          options.domOverlay = {root: document.body};
        }
        navigator.xr.requestSession('immersive-ar', options).then((session) => {
              session.mode = 'immersive-ar';
              xrButton.setSession(session);
              onSessionStarted(session);
        });
      }

      function requestViewerSpaceHitTestSource() {
        console.debug("Requesting hit test source.");
        xrSession.requestHitTestSource({
          space : xrViewerSpace,
          //space : xrLocalFloor, // WIP: change back to viewer
          //space : xrOffsetSpace, // WIP: change back to viewer
          offsetRay : new XRRay()
          //offsetRay : new XRRay({}, {y: -0.5, z: 1.0}) // WIP: change back to default
        }).then((hitTestSource) => {
          console.debug("Hit test source created.");
          xrViewerSpaceHitTestSource = hitTestSource;
        }).catch(error => {
          console.error("Error when requesting hit test source", error);
        });
      }

      function onSessionStarted(session) {
        useDomOverlay.disabled = true;
        xrSession = session;
        session.addEventListener('end', onSessionEnded);
        session.addEventListener('select', onSelect);
        session.addEventListener('inputsourceschange', onInputSourcesChange);

        session.requestHitTestSourceForTransientInput({
          profile : "generic-touchscreen"
        }).then(transient_input_hit_test_source => {
          console.debug("Hit test source for generic touchscreen created!");
          xrTransientInputHitTestSource = transient_input_hit_test_source;
        });

        if (debugSources) debugSources.startSession(session);

        if (!gl) {
          gl = createWebGLContext({
            xrCompatible: true
          });

          renderer = new Renderer(gl);

          scene.setRenderer(renderer);
        }

        session.updateRenderState({ baseLayer: new XRWebGLLayer(session, gl) });

        session.requestReferenceSpace('local').then((refSpace) => {
          xrRefSpace = refSpace;

          session.requestReferenceSpace('local-floor').then((localFloor) => {
            xrLocalFloor = localFloor;

            session.requestReferenceSpace('viewer').then((viewerSpace) => {
              xrViewerSpace = viewerSpace;

              xrOffsetSpace = xrViewerSpace.getOffsetReferenceSpace(
                new XRRigidTransform(new DOMPointReadOnly(0.1, 0, 0.5))
              );

              if (useReticle.checked) {
                requestViewerSpaceHitTestSource();
              }

              session.requestAnimationFrame(onXRFrame);
            });
          });
        });
      }

      function onEndSession(session) {
        session.end();
      }

      function onSessionEnded(event) {
        useDomOverlay.disabled = false;
        xrButton.setSession(null);
        xrSession = null;
      }

      function onCreateAnchor(anchor) {
        console.debug("Anchor created");

        anchor.context = {};

        let sceneObject = arObject.clone();
        sceneObject.visible = false;

        if (visualizeObjectSpace) {
          let xRay = new RayNode({direction : [5, 0, 0], baseColor : [1, 0, 0, 1]});
          let yRay = new RayNode({direction : [0, 5, 0], baseColor : [0, 1, 0, 1]});
          let zRay = new RayNode({direction : [0, 0, 5], baseColor : [0, 0, 1, 1]});

          sceneObject.addNode(xRay);
          sceneObject.addNode(yRay);
          sceneObject.addNode(zRay);
        }

        scene.addNode(sceneObject);
        flowers.push(sceneObject);

        anchor.context.sceneObject = sceneObject;
        sceneObject.anchor = anchor;

        // For performance reasons if we add too many objects start
        // removing the oldest ones to keep the scene complexity
        // from growing too much.
        if (flowers.length > MAX_FLOWERS) {
          let oldFlower = flowers.shift();
          oldFlower.anchor.delete();
          scene.removeNode(oldFlower);
        }
      }

      // Adds a new object to the scene at the
      // specificed transform.
      function addARObjectAt(frame, hitTestResult) {
        if ("createAnchor" in hitTestResult) {
          hitTestResult.createAnchor(new XRRigidTransform())
                          .then(onCreateAnchor)
                          .catch((err) => console.log("Anchor creation failed", err));
        } else {
          console.debug("Anchors not available, falling back to legacy approach.");
          // Fall back to the old approach:
          let sceneObject = arObject.clone();
          sceneObject.visible = false;

          if (visualizeObjectSpace) {
            let xRay = new RayNode({direction : [5, 0, 0], baseColor : [1, 0, 0, 1]});
            let yRay = new RayNode({direction : [0, 5, 0], baseColor : [0, 1, 0, 1]});
            let zRay = new RayNode({direction : [0, 0, 5], baseColor : [0, 0, 1, 1]});

            sceneObject.addNode(xRay);
            sceneObject.addNode(yRay);
            sceneObject.addNode(zRay);
          }

          sceneObject.matrix = hitTestResult.getPose(xrRefSpace).transform.matrix;
          sceneObject.visible = true;

          scene.addNode(sceneObject);
          flowers.push(sceneObject);

          // For performance reasons if we add too many objects start
          // removing the oldest ones to keep the scene complexity
          // from growing too much.
          if (flowers.length > MAX_FLOWERS) {
            let oldFlower = flowers.shift();
            scene.removeNode(oldFlower);
          }
        }
      }

      function DOMPointFromVec3(vector) {
        return { x : vector[0], y : vector[1], z : vector[2]}
      }

      let rayOrigin = vec3.create();
      let rayDirection = vec3.create();

      function onSelect(event) {
        if (useReticle.checked && xrViewerSpaceHitTestSource) {
          let results = event.frame.getHitTestResults(xrViewerSpaceHitTestSource);

          // Use the results to place our proxy object.
          if (results.length) {
            let hitResult = results[0];
            addARObjectAt(event.frame, hitResult);
          }

        } else if (!useReticle.checked && xrTransientInputHitTestSource) {
          let results_by_input_source = event.frame.getHitTestResultsForTransientInput(xrTransientInputHitTestSource);

          if (results_by_input_source.length && results_by_input_source[0].results.length) {
            let hitResult = results_by_input_source[0].results[0];
            addARObjectAt(event.frame, hitResult);
          }
        }

        // Test the cancel method.
        if (useReticle.checked && unsubscribeAfterTouch && xrViewerSpaceHitTestSource) {
          xrViewerSpaceHitTestSource.cancel();

          try {
            xrViewerSpaceHitTestSource.cancel();
            console.error("double-canceling hit test source should throw!");
          } catch(ex) {
            console.debug(ex);
          }

          xrViewerSpaceHitTestSource = null;
        }
      }

      function onInputSourcesChange(inputSourcesChangeEvent) {
        console.debug("Input sources changed!", inputSourcesChangeEvent);
      }

      // Set with all anchors tracked in a previous frame.
      let all_previous_anchors = new Set();

      // Called every time a XRSession requests that a new frame be drawn.
      function onXRFrame(t, frame) {
        let session = frame.session;
        session.requestAnimationFrame(onXRFrame);

        if (debugSources) debugSources.update(frame, xrViewerSpace);

        let pose = frame.getViewerPose(xrRefSpace);
        let viewerSpacePose = frame.getPose(xrViewerSpace, xrRefSpace);
        let offsetSpacePose = frame.getPose(xrOffsetSpace, xrRefSpace);
        let localFloorSpacePose = frame.getPose(xrLocalFloor, xrRefSpace);

        // Offset space visualization.
        if (visualizeOffsetSpace && offsetSpacePose) {
          offsetSpaceNode.matrix = offsetSpacePose.transform.matrix;
          offsetSpaceNode.visible = true;
        } else {
          offsetSpaceNode.visible = false;
        }

        if (visualizeLocalFloorSpace && localFloorSpacePose) {
          localFloorSpaceNode.matrix = localFloorSpacePose.transform.matrix;
          localFloorSpaceNode.visible = true;
        } else {
          localFloorSpaceNode.visible = false;
        }

        if ("trackedAnchors" in frame) {
          const tracked_anchors = frame.trackedAnchors;
          if (tracked_anchors) {
            all_previous_anchors.forEach(anchor => {
              if (!tracked_anchors.has(anchor)) {
                scene.removeNode(anchor.sceneObject);
              }
            });

            tracked_anchors.forEach(anchor => {
              const anchorPose = frame.getPose(anchor.anchorSpace, xrRefSpace);
              if(anchorPose) {
                anchor.context.sceneObject.matrix = anchorPose.transform.matrix;
                anchor.context.sceneObject.visible = true;
              } else {
                anchor.context.sceneObject.visible = false;
              }
            });

            all_previous_anchors = tracked_anchors;
          } else {
            all_previous_anchors.forEach(anchor => {
              scene.removeNode(anchor.sceneObject);
            });

            all_previous_anchors = new Set();
          }
        }

        if (useReticle.checked && xrViewerSpaceHitTestSource) {
          let results = frame.getHitTestResults(xrViewerSpaceHitTestSource);

          // Use the results to place our proxy object.
          if (results.length) {
            let hitResult = results[0];
            arObject.visible = true;
            arObject.matrix = hitResult.getPose(xrRefSpace).transform.matrix;
          } else {
            arObject.visible = false;
          }

        } else if (!useReticle.checked && xrTransientInputHitTestSource) {
          let results_by_input_source = frame.getHitTestResultsForTransientInput(xrTransientInputHitTestSource);

          if (results_by_input_source.length && results_by_input_source[0].results.length) {
            let hitResult = results_by_input_source[0].results[0];
            arObject.visible = true;
            arObject.matrix = hitResult.getPose(xrRefSpace).transform.matrix;
          } else {
            arObject.visible = false;
          }
        } else {
          arObject.visible = false;
        }

        scene.startFrame();

        scene.drawXRFrame(frame, pose);

        scene.endFrame();
      }

      // Start the XR application.
      initXR();
    </script>
  </body>
</html>
